Given from your history because of the tear, muscle weakness in the lower body is something what we can expect,so there can chances of reduced mobility in your hip joint, knee joint and ankle joint which leads to compensation or over use of the muscle so try to visit a physiotherapy Clinic near by and get a proper assessment done and slowly start working on your mobility, strength and agility
People with flat foot generally face issues like you have mentioned we have to work one you arch support which can reduced the tension to some extent and work on your ankle mobility and calf stretches and strengthening exercise, hope this helps
Next Steps
please try to have a proper assessment done regarding your issues and try to set a short and long term goal for the issues
Health Tips
using a warm tub and dipping your feet for 5 -10 min and wriggling your toes helps to improve the blood circulation and relaxes the foot muscles and try to do it 2 times daily after getting up and before going to bed